The condition for improving the properties of soil as well as the yield and quality of plants, as a result of fertilization with compost, is to use a stable and mature material. The degree of compost maturity can be evaluated, among others, basing on the content and properties of humus compounds. The aim of the research was to assess the changes in the content of ash, oxidizable total organic carbon as well as carbon of humus compounds in sewage sludge composted with a wheat straw addition. In addition, the aim of this work was to determine (basing on the obtained results) the degree of maturity of the produced compost. Mineralization of organic matter, which occurred during the composting process, resulted in lowering both the organic carbon content and the value of the C: N ratio, but increasing the ash content. Moreover, an increase in the content of carbon extracted from the compost with the mixture of 0,1 mol ∙ dm-3 Na4P2O7 + 0,1 mol ∙ dm-3 NaOH, and a decrease in the content of carbon extracted with distilled water were stated. The results of the carried out experiment indicated that the obtained compost was mature. ...
The aim of the three-year pot experiment was to determine the effect of standard mineral fertilization enriched with sulfur and iron on the content of nitrogen and sulfur in plants and on nutrient utilization by plants. Abundance of sulfates in soil after sulfur fertilization was also assessed. The direct effect of fertilization was assessed during the first and second year of the pot experiment, and the after-effect was analyzed during the third year. Rape (first year) and maize (second and third year) were the test plants. Solid mineral fertilizers (A: a mixture of ammonium nitrate and dolomite; B: a mixture of ammonium nitrate and sulfate) enriched with iron sulfate were used. Nitrogen content in the plants varied depending on applied fertilization as well on plant species and part. Sulfur application increased sulfur content in the aboveground parts of plants by 25-457% and in roots by 95-708%. Iron application ambiguously influenced nitrogen and sulfur content in the plants. Hovewer, simultaneous application of iron and sulfur (as fertilizer B enriched with iron) resulted in the highest coefficient of nitrogen (84%) and sulfur (39%) utilization. Sulfur fertilization caused a 5-20 fold increase in sulfate sulfur content in the soil. ...
